Abstract

This Brief Communication presents a numerical study of planar laminar flow over a backward facing step. The principal parameters are the expansion ratio (defined as the ratio of stepheight to channel height) and the Reynolds number (based on the maximum inflow velocity and the hydraulic diameter of the channel inlet). Results are presented for expansion ratios of 0.25–0.75 and Reynolds numbers from 50–900. The computed results are in close agreement with previous experimental and numerical results for expansion ratios of 0.5. The effect of the expansion ratio on the reattachment length is summarized as a function of the Reynolds number.